Activation of nuclear factor-kappaB in the rabbit spinal cord following ischemia and reperfusion

The transcription factor NF-kappaB is a ubiquitously expressed inducible regulator of a broad range of genes. Recent studies have shown that activation of NF-kappaB predominantly is associated with protecting cells from apoptosis, but in some cell models, it is associated with promoting cell death. We used a rabbit spinal cord model of reversible ischemia to determine whether NF-kappaB was activated by ischemic and reperfusion injury. DNA binding activity of NF-kappaB was analyzed by an electrophoretic mobility shift assay in animals subjected to varying durations of ischemia and reperfusion. A low level of constitutive NF-kappaB DNA binding was detected in normal lumbar spinal cord extracts. Animals subjected to a short ischemic insult of 15 min, from which they usually recover neurologic function, had a significant increase in the amount of active NF-kappaB in nuclear extracts after 18 h reperfusion. There was no change in nuclear NF-kappaB DNA binding in animals occluded for 60 min that are permanently paraplegic and exhibit extensive neuropathological damage. The amount of deoxycholate-releasable NF-kappaB sequestered in the cytosol, however, decreased after 18 h reperfusion in rabbits occluded for 60 min. This correlated with a decrease in the amount of RelA(p65) NF-kappaB subunit. The results suggest that activation of NF-kappaB after a limited ischemic injury may participate in a neuroprotective response and not in cell death.